This is a small grant proposal in response to RFA ES-06-007, "Biological effects of power frequency EMF." It has been hypothesized that EMF (electro-magnetic fields) may suppress melatonin, and through this mechanism, EMF might mediate morbidity and mortality. The problem may be particularly severe for elderly people who have low melatonin. The hypothesis that melatonin prevents aging, e.g., aging related to free-radical damage and cancer, has recently received sensational news coverage. Millions of Americans fearful of melatonin deficiency may be buying products from health food stores labeled as melatonin. The investigators propose to critically test whether EMF in the bedroom influences daily melatonin excretion. This small grant will permit the investigators to collect home EMF recordings to combine with data being collected for other projects on melatonin excretion and bedtime light levels. The correlation of EMF resultant vector strength and nightly melatonin excretion will be determine, to establish if EMF could be a substantial regulator of melatonin production. Statistical controls for age, gender, light levels, and drug intake will be implemented. This study will establish whether EMF could be an important source of variance in melatonin excretion. In conjunction with ongoing studies, possible indirect EMF effects through melatonin on morbidity and mortality will be considered.